This invention relates to a method and an apparatus for roughening a book block spine formed of compressed individual printed sheets by exposing the paper fibers or lifting out filler materials as the book block passes through a work station of an adhesive binder. The apparatus has a rotary roughening tool provided with tool bits penetrating into the book block spine.
In the processing of book blocks for adhesive binding, the folded printed sheets are assembled and then transferred into a clamping device of an adhesive binder in which they pass through processing stations of the adhesive binder.
The sheet folds are removed from the printed sheets, pressed into a book block spine, by a severing operation performed in the vicinity of the folds. Such a severing operation is effected, for example, in adhesive binders manufactured by the firm Muller Martini, by a circular knife rotated about a vertical axis, resulting in a relatively smooth spine surface. It has also been known to use milling tools for removing the folds. Such a spine surface, dependent upon the quality of the paper to be processed, has to be roughened in order to ensure a satisfactory bond of the upper surface of the book block spine with the adhesive utilized.
Conventionally, carbide grinding tools have been used for the subsequent roughening of the cut book block spine. As described by Alfred Furler in his book entitled "Adhesive Binding Technology" (published by Deutscher Drucker, Stuttgart, Germany), carborundum coatings are used which are mounted on a plate that rotates about a vertical axis as the book blocks are guided thereover.
It is a disadvantage of the prior art apparatus that the dust generated during the grinding operation clogs the free spaces of the Carborundum coating between the grinding core, resulting in a tendency to a breakdown of the roughening tool.